Comment by Gravityloss | Hacker News Reader

Comment by Gravityloss | Hacker News Reader

"DuPont’s configuration devised under COPPER CANYON had included no landing gear, orbital manoeuvring system or fuel reserves."

I've long held the opinion that the real lesson to take from NASP is that the higher the level of decision making, the more detached it is from physics or business.

Air breathing works for cruise (limited speed and altitude range, long duration, low thrust requirements).

Rockets work for acceleration (wide speed and altitude range, short duration, high thrust requirements).

Orbital missions are only about acceleration. Bringing very heavy air breathing engines to orbit doesn't make sense at all.

The lowest dry mass (=lowest cost) single stage to orbit vehicle designs tend to be dense propellant pure rockets.

In Finnish there's a saying "ajaa käärmettä pyssyyn": make the snake go into a gun barrel. An organization trying to achieve a needlessly hard thing because of political reasons. Closely related to Not Invented Here.

I'll go beyond "dense, propellant pure" rockets - the whole concept of single-stage vehicles is a pipe dream.

Staging is immensely important because it lowers the "order complexity" of carrying additional payload. In order to add payload you need to add fuel, and then you need to add more fuel to carry that fuel, and so on. This is immensely easier if you don't need to drag the dead weight of your initial stages along with you.

Single-stage is barely even feasible to orbit. Anything past that is just flatly science-fiction.

> In order to add payload you need to add fuel, and then you need to add more fuel to carry that fuel, and so on.

"The Tyranny of the Rocket Equation": https://www.nasa.gov/mission_pages/station/expeditions/exped...

With today's technology yes. Those that don't dream big however are destined to be replaced by tomorrow's technology.

That's rather naive. This isn't a failure to dream big. Everyone understands that SSTO will require major advances in propulsion and materials to be really practical and cost effective.

I agree with your thoughts on the decision making behind NASP. Even while it was still COPPER CANYON, doubts were being raised. Most of the big decisions to proceed seem to have been made after relatively brief presentations with limited technical detail or discussion. NASP was a case of selling a big picture without stopping to ask how possible it really was.

Personally, I find the X-33 more frustrating as this got far closer to flight and although it may never have led to VentureStar it would have been a great hypersonic testbed

Nowadays we do get critical articles about programs like the Joint Strike Fighter, but often they seem a little bit besides the point, for example comparing it to seventies design paradigms. The lightweight fighter mafia is emphasizing dogfighting, visual identification and gun kills, from an era when missiles were very unreliable and there was no stealth. I guess it would require a lot of expertise and access to rare information, to be able to evaluate the JSF on its own merits. Stillion and Sweetman have been the most interesting reads.

I think the problem with X-33 was that it was too big and risky for an experimental-only platform. If you want to develop things like aerospike engines or composite multilobe tanks, you should first have ground tests and then relatively small demonstrators using a lot of off the shelf technology. It makes no sense to bet so much stuff on a multi-faceted big expensive program that can fail when any of it components doesn't deliver. Or if you want to build something big, either use proven technology or retire risk in smaller programs first.

I guess people were emulating Apollo and the Space Shuttle. They had high performance but were not flexible or low cost, for a reason.

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